Help with a priest noob

I was originally going to go warlock got it to 58 and now just cant be bothered and think spriest looks funner. I'm level 70 atm should be 85 within the next week or two. Now I'm rather confused about gear talents etc currently im using http://www.noxxic.com/priest/shadow/dps-rotation for all my info.

could some kind spriest break down the main points that I'm going to have to do when i hit 85 to get prepared for raiding with my guilds alt runs?

*I'm the kind of guy who likes to prepare in advance and learn the class fast. Haven't played my priest in ages and when i did i was disc healing*

Read Kilee's Shadow priest guide that is a sticky here. Most of the commenters here also frequent shadowpriest.com. Both are great resources for anything you ever wanted to know about how to play a shadow priest.